Steering a commercial boat or large yacht can be similar to driving a heavy car with bad brakes. Its difficult to stop, and response to the rudder is slow. This poses no problem in the open sea, but it can be real challenge to maneuver the vessel in a congested marina or when docking. This is where a bow thruster comes in.
A bow thruster consists of an open-ended tube that runs through the underwater sections of the hull near the bow and perpendicular to the keel. A propeller mounted at some point inside this tube can rotate in either direction. The helmsman selects the rotational direction and actuates the propeller. As a result, the bow thruster sucks a solid stream of water in one end of the tube and forces it out of the other, pushing the bow sideways and augmenting the rudder to make steering more responsive.
Two Props are better than one
Traditional single propeller systems generate thrust by accelerating water in the axis of the propeller shaft. However, the water discharged